scholarly journals Patterns of Atmospheric 14C Changes

Radiocarbon ◽  
1980 ◽  
Vol 22 (2) ◽  
pp. 166-176 ◽  
Author(s):  
Minze Stuiver ◽  
Paul D Quay
Keyword(s):  
Solar Wind ◽  
Geomagnetic Field ◽  
Cosmic Ray ◽  
Solar Modulation ◽  
Production Rates ◽  
Climatic Fluctuation ◽  
The Past ◽  
Earth Magnetic Field ◽  
Carbon Reservoir ◽  
Cosmic Ray Flux

Natural atmospheric 14C changes are caused by fluctuations in upper atmospheric 14C production rates (Q) that are related to earth geomagnetic field variations and changes in solar wind magnetic shielding properties. Climate variability may also be responsible for some of the changes because it influences exchange rates of 14C between the various terrestrial carbon reservoirs.Upper atmospheric 14C production rates QM, in at/sec cm2 (earth), were calculated for the past 1200 years from the atmospheric 14C record and a carbon reservoir model. The changes in QM are compared in detail with the predicted Q variability derived from an Aa solar modulation mechanism and 20th century neutron flux observations. The influence of earth geomagnetic field changes on the magnitude of the solar wind modulation is discussed, and it is shown that the variations in this magnitude agree with the known differences in earth magnetic field intensity during the past 1200 years. The larger calculated QM oscillations during the sixth millennium bp also agree with this concept.Solar wind magnetic as well as geomagnetic forces modulate the incoming cosmic ray flux and explain the main features of the atmospheric 14C record. It is argued that climatic fluctuation is not a dominant cause.The oscillations between 3200 and 3700 BC, as measured by de Jong, Mook, and Becker, differ in rise time from those found for the current millennium.

scholarly journals Tritium and Argon-39 in Stone and Iron Meteorites

1969 ◽  
Vol 24 (2) ◽  
pp. 234-244 ◽  
Author(s):  
St. Charalambus ◽  
K. Goebel ◽  
W. Stötzel-Riezler
Keyword(s):  
Cosmic Ray ◽  
Decay Rates ◽  
Earth Atmosphere ◽  
Iron Meteorites ◽  
Production Rates ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
Cosmic Ray Flux

Tritium and argon-39 measurements of stone and iron meteorites are reported and discussed. The tritium values of stone meteorites are in general higher than those found in other laboratories. The tritium decay rates in irons were low but a relatively high tritium value was measured in the rim of the meteorites. Factors which may influence the production rates are discussed and it is concluded that the average cosmic-ray flux which irradiated the meteorites must be at least a factor of two higher than the values reported by MacDonald for the cosmic-ray intensity at the top of the earth atmosphere.

Constancy of Cosmic-Ray Flux over the Past 30 000 Years

1953 ◽  
Vol 90 (4) ◽  
pp. 713-714 ◽  
Author(s):  
J. Laurence Kulp ◽  
Herbert L. Volchok
Keyword(s):  
Cosmic Ray ◽  
The Past ◽  
Cosmic Ray Flux

scholarly journals Modeling of Atmospheric Radiocarbon Fluctuations for the Past Three Centuries

Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 249-258 ◽  
Author(s):  
P E Damon ◽  
R S Sternberg ◽  
C J Radnell
Keyword(s):  
Magnetic Field ◽  
Fossil Fuels ◽  
Magnetic Field Intensity ◽  
Cosmic Ray ◽  
Solar Modulation ◽  
Geomagnetic Index ◽  
The Past ◽  
Dipole Magnetic Field ◽  
Climatic Time Series ◽  
Sunspot Record

Relatively precise quantitative observations of geophysical parameters are available to evaluate the fluctuations of atmospheric 14C activity during the past three centuries. As reviewed by Damon, Lerman, and Long (1978), these fluctuations seem to result from three factors: 1) changes in the earth's dipole magnetic field intensity, which has been decreasing since the first measurements by Gauss (McDonald and Gunst, 1968); 2) solar modulation of the cosmic-ray production, which has been correlated with the sunspot record of Waldmeier (1961), and more recently, to the Aa geomagnetic index by Stuiver and Quay (1980); and 3) the combustion of fossil fuels (Suess, 1955). A relationship between the climatic time series and the 14C-derived record of solar change has not yet been demonstrated (Stuiver, 1980).

ENERGETIC PARTICLES IN THE HELIOSPHERE

2005 ◽  
Vol 20 (29) ◽  
pp. 6621-6632 ◽  
Author(s):  
BERND HEBER
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Cosmic Rays ◽  
Energetic Particle ◽  
Current Knowledge ◽  
Cosmic Ray ◽  
Interplanetary Shock ◽  
The Sun ◽  
Local Interstellar Medium ◽  
Cosmic Ray Flux

The heliosphere is the region around the Sun that is filled by the solar wind and its embedded magnetic field. The interaction of the supersonic solar wind with the local interstellar medium leads to a transition from supersonic to subsonic speeds at the heliospheric termination shock. The latter is regarded to be the source of the anomalous component of cosmic rays. Within the heliosphere "local" energetic particle sources, like the Sun and interplanetary shock waves contribute to the cosmic ray flux, too. At energies below a few GeV the observed galactic and anomalous cosmic ray intensities are modulated by the heliospheric magnetic field. In my contribution, both the current knowledge and hypotheses about modulation and the transport of cosmic rays in the heliosphere are reviewed.

Fluctuations of atmospheric carbon-14 concentrations during the past century

1971 ◽  
Vol 321 (1544) ◽  
pp. 105-127 ◽  
Keyword(s):  
Solar Activity ◽  
Production Rate ◽  
Cosmic Ray ◽  
Solar Modulation ◽  
Past Century ◽  
Activity Maximum ◽  
Carbon 14 ◽  
The Past ◽  
Natural Carbon ◽  
Atmospheric Carbon

Variations in atmospheric carbon-14 concentrations during the past century have been studied through the analyses of wines, spirits and plant seeds. The results reveal that short-term fluctuations of carbon-14 concentrations have occurred which are negatively correlated with solar activity. Maximum correlation occurs with carbon-14 concentration minima preceding sunspot maxima by one year. The overall magnitude of the fluctuations, 3 % of the natural carbon-14 concentration, appears too large to be attributed to variations in the isotope production rate by solar modulation of the galactic cosmic ray flux. It is proposed that the fluctuations are the result of solar-sensitive mixing of stratospheric and tropospheric air masses through variations of the incident ultraviolet and corpuscular radiation over each solar cycle. Theoretical considerations require that stratospheric carbon-14 levels fluctuate in direct correlation with solar activity. These variations of natural carbon-14 activities in the troposphere represent a significant deviation from the basic assumption of the radiocarbon dating method and may introduce further uncertainty in the dating of ‘young’ materials. In addition, they endorse the universal use of the N. B. S. modern standard in carbon -14 assay. A long-term decrease in tropospheric carbon-14 concentrations was also observed and is attributed to a reduction in the mean production rate of carbon-14 through enhanced solar activity.

Cosmic-Ray Anisotropies as a Function of Time and Direction

1968 ◽  
Vol 1 (3) ◽  
pp. 114-115
Author(s):  
J.G. Ables
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Energy Range ◽  
Interplanetary Medium ◽  
Large Angle ◽  
Cosmic Ray ◽  
Angle Scattering ◽  
Large Angle Scattering ◽  
High Degree ◽  
Cosmic Ray Flux

The cosmic ray flux in the energy range 100 MeV/nucleon ≤ E ≤ 1 GeV/nucleon is remarkable for its high degree of isotropy. Observed deviations from isotropy seldom exceed a few per cent and are commonly much smaller. The mechanism responsible for this isotropy is presumed to be multiple, large-angle scattering of the charged cosmic ray particles by irregularities of the interplanetary magnetic field. While generally precluding any hope of discovering a source-related anisotropy of the flux in this energy range, it is just this strong interaction of the cosmic rays with the interplanetary medium that allows the study of the small observed anisotropies, both persistent and transient, to yield considerable information about the structure of the interplanetary medium (the solar wind and its entrapped magnetic field).

scholarly journals Variações de intensidade do campo geomagnético em Santa Maria (Brasil) para os últimos 3 mil anos

2018 ◽  
Vol 40 ◽  
pp. 7
Author(s):  
Everton Frigo ◽  
Gelvam Hartmann
Keyword(s):  
Geomagnetic Field ◽  
Climate Changes ◽  
Internal Field ◽  
Outer Core ◽  
The South ◽  
The Past ◽  
Earth Magnetic Field ◽  
Electrically Charged ◽  
Santa Maria ◽  
Magnetic Field Variations

Earth magnetic field variations at secular scales and at hundred quilometers have internal origin at the outer core. The most important feature associated with this internal field is the South Atlantic Magnetic Anomaly (SAMA), which covers the South America and it is characterized by the lowest total field intensity at the surface. Here, we investigate the geomagnetic field variations in Santa Maria (Brazil) over the past 3 ka. Results indicate that the intensities observed in Santa Maria are the lowest of the geomagnetic field over the past 3 ka. The consequences of these field features could be the increase in the electrically charged particles reaching the low Earth atmosphere that may generate problems in the communications systems or climate changes.

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